ST Waveform Analysis of Fetal ECG & Intrapartum Hypoxia


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Dr. Di Renzo “Hello everyone, my name is Gian Carlo Di Renzo. I’m Professor of Obstetrics and Gynecology and Perinatal Medicine at the University of Perugia and now I’m also President of the European Association of Perinatal Medicine. Today I would like to talk to you about the new frontiers of intrapartum fetal monitoring. We have Professor Karl Rosen, who is Chief Medical Director of Neoventa. 

Professor Rosen has developed with coworkers new methodologies for looking at intrapartum hypoxia better than before. Now as many of you know, cardiotocography is the major tool for intrapartum monitoring and monitoring the fetus in any condition during labor. Labor is a normal stressful condition but should be a natal stress condition and not a distress condition from the fetus. As you know, cardiotocography has a lot of pitfalls due to the low sensitivity and this is linked with the fact that we have increased a lot of unnecessary intervention. Therefore, we may probably increase all the operative deliveries especially in some countries like in Italy and most of the European countries will increase a lot of caesarian sections for what we call fetal distress which is really not fetal distress. Now in the obstetrical arena many have looked to the possibility to improve this methodology through computerized systems but I think the new age is coming with new developments on the available use of fetal electrocardiography. Now Karl, can you just introduce briefly what the basics of this new methodology are and how we can apply it for clinical use?”

Professor Rosen: “The aim with this work that’s been ongoing for more than twenty-five years has been to see if we could diagnose intrapartum hypoxia. As you know, the electrocardiogram provides very good information on the condition of the heart under stress in the adult, and labor is a stressful so wouldn’t there be ST waveform changes? That was the theory some thirty years ago, and then we’ve taken this concept through extensive animal work performed in Sweden and in the UK and we said we need new technology to be able to retrieve the ST. We then had a series of devices named stand units developed over the years. Now with the latest development in digital signal processing, we are able to present to the clinician the information contained in the ST and there we are also using modern expert system tools to guide the clinician in labor and the midwife as well, thereby providing accurate information on the fetal state. Now just to touch on the physiology here...”

Dr. Di Renzo “I think it is very important that you express some of the basics about the ST waveform - how you concentrate on that ST waveform because it so important for myocardial action and for the evaluation of hypoxia. Can you tell us something about it?”

Professor Rosen: “We have here the electrocardiogram from the fetus. Now the fetus is in a situation where the majority are capable of responding to the stress of labor. What we then detect is an increase in T-wave amplitude as a consequence of the use of myocardial glycogen stores. These are stores that nature has provided the fetus with and they are the most important defense that’s available in labor. What we are doing is we are detecting the change by looking at T-wave height and we have a T upon QRS ratio. Then we’re also detecting the situation when the fetus is not capable of responding and that’s where we see ST depression, they get their T-waves. We then let the computer go in and detect these changes in labor providing direct guidelines of episodic changes, baseline changes, and also these biphasic abnormal waveforms. Here you have examples of cases and this has now been tried in two randomized control trials.”

Dr. Di Renzo “So you are now dealing with the randomized control trial and just recently a big randomized control trial finished in Sweden and is going to be published. I think the results are very encouraging and in some way definitely for the clinical application of this methodology in our routine labor ward facts. What do you have to say about this randomized trial?”

Professor Rosen: “It’s a multicenter trial so we are talking about the three busiest units in Sweden. It’s a trial that’s gone on for eighteen months and 4,500 babies, and I’m very pleased to say that we have reduced the number of babies suffering from intrapartum hypoxia by 75%. If the technology has been used accurately, no baby entered neonatal intensive care and, furthermore, the number of operative interventions have been reduced by 45%.”

Dr. Di Renzo “That is the aim that we want to obtain. I think everyone should know, but maybe they don’t, that this system is applied to the simple scalp electrode we normally use for the ECG tracing, internal tracing or when there is any suspicious tracing by ultrasound or transabdominal monitoring of CTG, you know everyone of us may decide to break the membranes and put a scalp electrode to better understand what is going on in the fetal heart rate beat. In this case, we have an additional evaluation by a computer system, which provides information that Karl Rosen has just depicted for you. The European union has funded a very big project which Karl Rosen is a Project Leader and participating centers are all around Europe. I’m privileged to have the center in Italy to carry on this research in which I think the aims are slightly different from a randomized trial but not so very important because I think that we support two major aims. Can you tell us what are the major aims of this European legal union trial we are already starting?

Professor Rosen: “Yes, the situation when something like this has been developed is that we want to secure the safe use of this technology. It is one thing when an academic center develops something, but when an industry is producing a machine I believe the most important thing is to make sure that it actually works in clinical medicine. Now what the EU Commission has provided us with is one of the biggest grants and allowing us to set up centers of excellence. These are obstetric well-known centers that will then be given a regional responsibility and serve as a hub of experience. Obviously every case will be monitored, and we’ll make sure that the guidelines, which we have on the use of ST and CTG will be followed and staff will be certified. The aim with this is to enhance obstetrics and make sure that the physiology that we believe is relevant could be made full use of in labor in order to achieve the extraordinary results of the Swedish Randomized Trial in providing a better care for the women for the next…”

Dr. Di Renzo: “I’d also like to point out that a normal cardiotocography machine a little bit better shape, let’s say, according to the new wave of architectural design is already on the market and is provided by a company in Goteborg, Sweden called Neoventa Medical. I think it can also be available in any of the European countries. It’s practically like buying a cardiotocograph with the advantage you seem to have a more accurate evaluation of intrapartum hypoxia and this is because we are dealing with the most important organ that can be affected by intrapartum hypoxia, which is obviously the heart. So we’re going within the heart to look into the myocardial function and from that we extrapolate the real value of these ECG segments. I think Professor Rosen has been very convincing and also the result that’s been received and now human studies. This a new frontier, I think in this way we may face the criticism to our obstetricians to be not only very technological in their approach in the labor ward and humanitarians and at the same time we’re increasing also our subjugal approach. We are closing the natural way of birth and due to, I think, that fetal distress will be a very limited option in the caesarian section area because it would be limited by the more accurate evaluation. So when there is fetal distress, it will be a real fetal distress and not like it is now. We do a lot of caesarian sections and the baby comes out perfectly normal because obviously our cardiotopography readings have been misleading or very low sensitivity as it detects actually. I think these add something really new and I hope you interact with us at our site. If you have any questions for Professor Rosen or me, please ask through the site. We may interact a little and give you more of an explanation on this. Thank you very much.”

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